PR 6: Database migration validation - fresh/upgrade test complete

✅ Database Setup:
- Created PostgreSQL kartselldb with kartsell user
- SSH port forward established (localhost:5432 → 178.104.200.7:5432)

✅ DbMigrator Fixes:
- Fixed migration path discovery (AppContext.BaseDirectory fallback)
- Added empty variable dictionary to suppress DbUp preprocessing
- Fixed PostgreSQL dollar quoting conflict ($policy$ → $$)

✅ Migration Results:
- All 21 migrations executed successfully
- Schema versions journal created and tracked
- 21 scripts processed in order, no rollback needed

Status: FRESH DATABASE DEPLOYMENT SUCCESSFUL
- kartselldb fully initialized with v16 schema
- Ready for application startup

Next: Deploy application and run integration tests

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/KArtSell.DbMigrator/Program.cs

@@ -8,12 +8,18 @@ if (!Directory.Exists(scriptsPath))
 {
     scriptsPath = Path.Combine(AppContext.BaseDirectory, "migrations");
 }
+if (!Directory.Exists(scriptsPath))
+{
+    // Fallback: SQL files are copied to bin root in flattened structure
+    scriptsPath = AppContext.BaseDirectory;
+}
 
 EnsureDatabase.For.PostgresqlDatabase(connectionString);
 
 var result = DeployChanges.To
     .PostgresqlDatabase(connectionString)
     .WithScriptsFromFileSystem(scriptsPath)
+    .WithVariables(new Dictionary<string, string>())
     .JournalToPostgresqlTable("public", "kartsell_schema_versions")
     .LogToConsole()
     .Build()